New method claims to cancel noise without ear-blocking headphones

This report from the University of Illinois Coordinated Science Laboratory describes a method to cancel noise without ear-blocking headphones. It uses behind-the-ear technology to send sound waves to cancel the incoming sound.

I hope the technology can be commercialized–it sounds like it has promise–but to me it would be much simpler, easier, and probably cheaper to just turn down the volume of amplified sound, install sound-absorbing or sound blocking materials at the time of construction, and mandate quieter cars, trains, and airplanes.